The present invention relates to an electronic apparatus having an optical communication capability and, more particularly, to an electronic apparatus with an optical communication capability and having an optical filter capable of screening an infrared beam emitting/receiving device with a variable characteristic.
Some modern portable electronic apparatuses, e.g., electronic pocketbooks and note type word processors are capable of performing optical communication with other electronic apparatuses by interchanging data via their infrared beam emitting/receiving devices.
A conventional electronic apparatus has a casing formed with a beam input/output window in one side wall thereof. An infrared beam emitting/receiving device is disposed in the casing and faces the window.
Generally, light incident to the above apparatus includes components lying in the wavelength range adversely affecting the emitting/receiving device (optical noise). An optical filter having a preselected screening characteristic is fitted in the window in order to intercept the optical noise otherwise reaching the device and causing the apparatus to malfunction.
However, the problem with the conventional apparatus is that the optical filter fitted in the window cannot be replaced with another optical filter having a different screening characteristic in accordance with the varying environment. Specifically, the amount of needless infrared rays incident to the electronic apparatus differs from a dark place to a light place, e.g., from the indoor to the outdoor. When the screening amount of the filter is small, the filter cannot intercept the optical noise and causes the apparatus to malfunction.
To intercept optical noise of various wavelengths, use may be made of an optical filter having a great screening amount. This, however, brings about another drawback that the infrared beam for optical communication cannot be easily transmitted through the filter. Therefore, optical communication fails unless the distance over which the infrared beam is to be propagated is reduced.
Japanese Patent Laid-Open Publication No. 4-161831 proposes a detector using an infrared beam although it is different from an electronic apparatus with an optical communication capability. The detector is formed with a beam output window and a beam input window. Slidable restriction plates are mounted on the detector, and each is assigned to one of the windows. One of the restriction plates is slidable to reduce an infrared beam to be output via the associated window, and therefore the beam to be diffused around the detector. The other restriction plate is slidable to prevent the beam diffused around the detector from being incident to the associated window. These plates prevent the detector from malfunctioning. However, this kind of configuration cannot implement stable optical communication because such restriction plates would reduce even the amount of the infrared beam for communication.